Re: drop duplicate buffers in OS

(2014/01/16 21:38), Aidan Van Dyk wrote:
> Can we just get the backend that dirties the page to the posix_fadvice DONTNEED?
No, it can remove clean page in OS file caches. Because if page is dirtied, it 
cause physical-disk-writing. However, it is experimental patch so it might be 
changed by future benchmark testing.

> Or have another helper that sweeps the shared buffers and does this post-first-dirty?
We can add DropDuplicateOSCache() function to checkpointer process or other 
process. And we can chenged posix_fadvice() DONTNEED to sync_file_range(). It can 
cause physical-disk-writing in target buffer, not to free OS file caches.

I'm considering that sync_file_range() SYNC_FILE_RANGE_WAIT_BEFORE | 
SYNC_FILE_RANGE_WRITE in executing checkpoint. It can avoid fsync freeze 
situaition in part of of finnal checkpoint.

Regards,
--
Mitsumasa KONDO
NTT Open Source Software Center